Ed Miliband, who beat his brother to become Labour leader on Saturday, apparently looked on, not knowing what to do.

Shackleton was also present on Saturday when the five leadership contenders were told privately of the result before the public announcement. Robinson reported on Today this morning that she was "absolutely furious" then, too.

Since that shock defeat, Shackleton has been a constant presence at her husband's side. Standing in the wings of stages where he continues to deliver fringe speeches, she can usually be seen smiling, never allowing her eyes off him.

Shackleton may well be happy that, after an arduous campaign, she will see more of her husband again.

The four-month long contest campaign profoundly affected their family life, with David Miliband often coming home from far-flung places late at night after the rest of his family had gone to sleep.

But if she were angry, it would hardly be a surprise. Most in David Miliband's camp are downcast at the result and prone to flashes of anger at the process they endured, only to lose by a whisker to his younger brother.

Shackleton, an accomplished concert violinist, shared her husband's ambitions: she has a similarly clear mind and doesn't suffer fools.

She will have agreed completely he should be the next leader of the Labour party. Indeed, the Telegraph reported that she was "full square" behind his aborted plans to act against Gordon Brown in 2008.

However, she is said by some friends to have been profoundly upset for some time at Ed Miliband's decision to run, and her anger has taken others within the family aback.

It could well take David Miliband and his family some time to decide what to do next.